Printers mark images on a medium. To achieve acceptable quality in output, the printed image must be properly aligned on the medium, and as a consequence, printers are designed with anti-skew mechanisms to insure such alignment.
Skew is an oblique course or a deviation from a predetermined straight line. For example, as paper is fed through a printer, it may buckle or twist. If an image is then printed, it will be skewed.
Skew can be caused by many factors. For instance, a printer may feed paper irregularly-driving one side more than the other, with the outcome that different lines of the printed image will not be parallel. Additionally, when paper is initially fed into a printer, it may not be properly aligned. If so, the image will be incorrectly positioned on the page. Often, as paper is fed through a printer, the paper is forced to make a significant turn. Because the paper resists turns, it may move away from the drive mechanism and cause a skewed print image. Variations in parts, media and product handling may also cause skew.
To prevent skew, printers are usually equipped with special paper guides and intricate drive mechanisms. Hewlett-Packard's DeskJet.RTM. printer, as disclosed in U.S. Pat. No. 4,728,963, is an example of a printer with effective anti-skew features.
Nevertheless, even the best presently existing printers often print skewed images. This invention offers a printer featuring significantly improved anti-skew design.